1. Field of the Invention
The present invention relates to a portable terminal device such as a cellular telephone or personal digital assistant (PDA) comprised by mutually and pivotally coupling two cases.
Priority is claimed on Japanese Patent Application No. 2003-307224, filed on Aug. 29, 2003, the content of which is incorporated herein by reference.
2. Description of Related Art
An example of a conventional portable terminal device had two cases and was provided with a coupling section that mutually and pivotally couples the two cases arranged so as to be able to be mutually overlapped about an axis along the direction in which both cases are overlapped (see, for example, Japanese Unexamined Patent Application, First Publication No. H07-288860). In a portable terminal device employing this type of constitution, a through hole is formed in a rotation shaft that composes the coupling section that allows the inner space of the two cases to mutually pass through. A cable is disposed in this through hole that mutually electrically connects circuit boards arranged within the two cases. This cable transmits electrical signals which are exchanged between the circuit boards arranged in both cases, and power is supplied to one of the cases from a battery provided in the other case.
In this type of portable terminal device, since the cable is twisted in the pivoting direction when the two cases are mutually pivoted, the relative pivoting range of the two cases is restricted for the purpose of preventing disconnection of the cable as a result of this twisting. In addition, the rotation shaft is rotatably supported relative to one case by a bearing section provided in the other case.
However, in a conventional portable terminal device, when a user has applied external force that causes the two cases to mutually pivot beyond the predetermined pivoting range, force acts which attempts to incline the center line of the rotation shaft towards the axis, and since stress concentrates in the bearing section and case mounting section that anchors the bearing section, there was the risk of damage to the case mounting section because its strength was not that particularly high.
Furthermore, although forming the case provided with the bearing section to have greater thickness was considered as a way of resolving this problem, due to the requirements in recent years for reduced size and thickness of portable terminal devices for the purpose of improving the portability of portable terminal devices, this solution is not desirable.